Relationship of 13 C to Vicinal 1 H Coupling to the Torsion Angle in Uridine and Related Structures

Abstract

Uracil was prepared enriched at C2 with carbon-13 and converted into uridine from which 2,5′-anhydro-1-β-D-ribo-furanosyl and 2,2′-anhydro-1-β-D-arabino-furanosyl uracil were prepared. The 13 C2 to vicinal proton coupling constants for these compounds were measured and are compared in terms of the expected torsion angles defined by the two atoms. The evidence suggests the existence of a Karplus-type relationship as is found for vicinal proton coupling. The data establish the anti conformation for uridine in solution.